EP3182063B1 - Method for determining a current wheel diameter - Google Patents

Description

Background of the Invention

1. a) Hinterlegen eines Ausgangswerts des Raddurchmessers,
2. b) Messen eines Drehgeschwindigkeitsparameters des Rades für einen Messzeitpunkt t_i (i = 1 ... n),
3. c) Bestimmen einer von dem Drehgeschwindigkeitsparameter unabhängigen Referenzgeschwindigkeit zum Messzeitpunkt t_i,
4. d) Ermitteln eines Schätzwerts eines Raddurchmesserparameters für den Messzeitpunkt t_i ausgehend von der in Schritt c) bestimmten Referenzgeschwindigkeit und dem in Schritt b) gemessenen Wert des Drehgeschwindigkeitsparameters des Rades,
5. e) Wiederholen der Schritte b) bis d) für verschiedene Messzeitpunkte t_i,
6. f) Bestimmen eines Korrekturwerts des Raddurchmessers für einen Auswertezeitpunkt aus den ermittelten Schätzwerten.

The invention relates to a method for determining a current wheel diameter of a wheel of a vehicle, in particular a rail vehicle, comprising the steps:

1. a) depositing an initial value of the wheel diameter,
2. b) measuring a rotational speed parameter of the wheel for a measuring time t _i (i = 1 ... n),
3. c) determining a reference speed independent of the rotational speed parameter at the measurement time t _i ,
4. d) determining an estimated value of a wheel diameter parameter for the measurement instant t _{i on} the basis of the reference speed determined in step c) and the value of the rotational speed parameter of the wheel measured in step b),
5. e) repeating steps b) to d) for different measurement times t _i ,
6. f) determining a correction value of the wheel diameter for an evaluation time from the determined estimated values.

Such a method is known from the US 8,874,345 B2 known. In the method there, the numerical value of the initial value is replaced by the numerical value of the correction value based on a difference in the speeds.

Distance and driving speed measurements are often determined as a function of the number of wheel revolutions of the vehicle in question. With train protection systems in particular, it is necessary to know the wheel diameter down to 3 mm.

The determination of a driving speed of a vehicle by means of a speed sensor requires knowledge of a rolling circumference of a wheel rolling on a road, the speed of which is measured by the speed sensor. The same applies accordingly to the measurement of a distance traveled on the basis of a count of the revolutions of the wheel. The rolling circumference of the wheel is usually calculated from a wheel diameter. The wheel diameter can be measured with relatively little effort before the wheel is mounted on the vehicle, unless it is already known from the manufacture of the wheel.

However, the wheels of a vehicle, such as a rail vehicle, that roll on a roadway, such as a rail, wear out during operation of the vehicle. For precise measurement of the driving speed and driving distance using rotary sensors, it is therefore necessary to know the current wheel diameter of the wheel. For example, the wheel diameter of a rail vehicle in operation can be reduced by 12% compared to an initial value. It is then an exact determination of the driving speed and distance from the information relating to the wheel rotation, in particular with a deviation of the measured value from the true value of a maximum of 0.3% (in the case of a wheel diameter) that is permissible in rail traffic of, for example, 1000 mm corresponding to plus-minus 3 mm), no longer possible.

Therefore, the current wheel diameter must be determined regularly during the operating life of the vehicle. In the case of rail vehicles, this is typically carried out manually at relatively great expense as part of maintenance measures. There is also the risk of incorrect measurement or incorrect input of the measured value during manual re-measurement.

As an alternative to this, it is known to carry out calibration runs on selected reference routes with precisely measured reference points. This procedure also requires a great deal of effort in terms of setting up the reference routes and regularly performing the calibration runs. In addition, the vehicle is typically not available for its actual purpose during the calibration runs.

The one from the US 8,874,345 B2 Known methods for automatically correcting the stored size of a wheel, a deviation between a speed of a vehicle determined on the basis of a rotational speed parameter of a wheel and the stored size of the wheel and an independent reference speed of the vehicle is determined and an estimated value for the size of the wheel is calculated therefrom. Based on this, the stored value for the size of the wheel is corrected. However, there is a risk that errors in the determination of the reference speed that is independent of the rotational speed parameter will not be recognized, so that ultimately an incorrect correction value for the size of the wheel is determined. This can be particularly problematic if the speed and distance of the vehicle are evaluated as part of a train protection system. This is particularly dangerous if, for example, a wheel diameter that is too small is determined, since the values for driving speed and driving distance determined from the wheel rotation are then smaller than the actual values.

Object of the invention

It is therefore an object of the invention to provide a method which allows a current wheel diameter of a wheel of a vehicle to be determined reliably, precisely and safely while the vehicle is in operation.

Description of the invention

This object is achieved according to the invention by a method according to claim 1.

The invention provides that an expected value of the wheel diameter for the evaluation time is determined on the basis of the initial value of the wheel diameter and a value of a first mileage parameter of the vehicle, and that the correction value is compared with the initial value of the wheel diameter and the numerical value of the initial value by the numerical value of the Correction value is only replaced if the correction value is at least a minimum deviation less than the initial value, and if the difference in amount between the correction value and the expected value is below a plausibility limit.

The replacement of the numerical value of the initial value by the numerical value of the correction value is also referred to below as step g).

By determining an expected value of the wheel diameter on the basis of the value of the first mileage parameter, it is possible to carry out a plausibility check for the correction value. The expected value describes how large the diameter of the wheel should be based on experience with the current value of the first mileage parameter. The expected value can be calculated, for example, by subtracting a wear amount proportional to the value of the first mileage parameter from the initial value. According to the invention, known information (for example from experiments or experience) about the wear behavior of the wheel depending on the first mileage parameter in the process.

The first mileage parameter can in particular contain information relating to an operating time of the vehicle, a distance traveled by the vehicle, and sum information about a course of the vehicle Longitudinal vehicle acceleration, preferably weighted with the total mass of the vehicle or a train containing the vehicle and / or total information about a profile of a force acting on the vehicle coupled to the vehicle. When determining the expected value, the value of the first mileage parameter is typically selected in accordance with the evaluation time t _{a used} for determining the correction value in step f).

By comparing the difference in amount of the correction value and the expected value with the plausibility limit value, it can be ensured that any measurement errors that occur in step b) and / or in step c) and / or arithmetic errors (for example due to incorrect programming or electronic defects) in step d) and / or in step f) do not lead to a grossly incorrect numerical value of the correction value for the wheel diameter being set in step g). The plausibility limit for the difference between the correction value and the expected value can be defined absolutely (e.g. 0.3 mm) or relative (e.g. 0.03%) to the correction value or expected value.

By specifying the minimum deviation between the correction value and the output value, it can be achieved that the numerical value of the output value is only replaced by the numerical value of the correction value if the wheel diameter has decreased significantly. It is thereby avoided that even the smallest changes in the wheel diameter lead to frequent adaptation of the numerical value of the initial value. Such excessively frequent adaptations could, under certain circumstances, lead to consequential errors over time (ie when the method according to the invention is used many times) and thus to considerable deviations of the current numerical value of the initial value from the true value of the current wheel diameter. According to the invention, this risk can be avoided by specifying the minimum deviation. The minimum deviation can be defined absolutely (eg 0.5 mm) or relative (eg 0.05%) to the initial value.

The speed of rotation parameter is typically a speed of rotation of the wheel, in particular measured as speed (number of revolutions around a wheel axis per unit of time). The speed of the wheel is preferably measured directly on the wheel or on an axis connected to the wheel in a rotationally fixed manner. Alternatively, the rotational speed parameter can also be a rotational speed of a shaft, the rotational speed of which is in a known, in particular fixed, relationship to the rotational speed of the wheel. For example, a rotational speed of a transmission shaft of a transmission or a rotational speed of a motor shaft of a drive motor acting on the wheel can be considered.

The reference speed, which is independent of the rotational speed parameter, can be calculated from a time period which is required to drive through a measuring section with a known length. The measuring section can be set up with a known length. Alternatively, the length of the measurement section can be determined using a position determination system, such as GPS. The reference speed is preferably measured with an accuracy which is better than an accuracy for the updating of the wheel diameter defined by the plausibility limit value.

The wheel diameter parameter is in a known relationship to the wheel diameter. The wheel diameter parameter is preferably the wheel diameter itself. Alternatively, for example, a radius of the wheel or a rolling circumference of the wheel can be considered. When determining the estimated value for the wheel diameter parameter in step d), in particular a quotient can be calculated from the reference speed and the rotational speed parameter. Typically, in step d) an undeformed, in particular circular, slip-free rolling wheel is assumed.

By repeating steps b) to d), a family of estimated values of the wheel diameter parameter is obtained for different measuring times t _i . This set of estimates also contains information in particular on the progression of the estimated values with the progression of the time, which is expressed in the assignment of an estimated value to the respective measurement time t _i . This information can be taken into account when determining the correction value of the wheel diameter as described below. In the simplest case, the correction value can be selected as the last estimated value. As an alternative, it is conceivable to calculate the correction value as an average of the estimated values, it being possible for weighted later to be given greater weight. Particularly advantageous variants of the calculation of the correction value are also shown below.

If the conditions according to the invention described above are met, the numerical value of the initial value is replaced by the numerical value of the correction value. The method according to the invention is then preferably carried out again. By replacing the output value with the correction value in step g), a new output value is stored in accordance with step a) for the following process run.

Preferred variants of the method according to the invention

In an advantageous variant, it is provided that the estimated values determined in step d) are each assigned a value of the first mileage parameter, and that in step f) the correction value of the wheel diameter is determined by a compensation calculation from the estimated values and the assigned values of the first mileage parameter. By assigning a value of the first mileage parameter to the respective estimated values, a development of the wheel diameter over a wear-triggering stress, which is expressed by the first mileage parameter, can be better represented than by assigning the respective measurement time t _i . The compensation calculation can include determining a compensation line using the method of least squares and evaluating it for a value of the first mileage parameter. In particular, the value of the first mileage parameter at the time step f) is carried out during the evaluation the compensation calculation can be used. This corresponds to an extrapolation beyond the last measurement time t _n . As a result, the correction value can be determined particularly precisely if the value of the first mileage parameter has risen significantly since the last measurement time t _n . Alternatively, the value of the first mileage parameter at the last measurement time t _n , at which steps b) and c) were carried out, can be used to evaluate the compensation calculation. This corresponds to a determination of the correction value for this last measurement time t _n ; ie t _a = t _n . This is particularly useful if step f) is carried out immediately after the last measurement time t _n .

A variant is also preferred in which it is provided that the estimated values determined in step d) are each assigned a value of at least two mileage parameters, that in step f) an intermediate correction value of the wheel diameter for each mileage parameter is made by a compensation calculation from the estimated values and the assigned values of the respective mileage parameter is determined, and that the correction value is determined from the intermediate correction values, preferably the largest intermediate correction value being used as the correction value. A value of a first mileage parameter and a value of a second mileage parameter are thus assigned to each estimated value. A value of a third mileage parameter is preferably also assigned to each estimated value. In particular, the following can be used as mileage parameters: an operating time of the vehicle, a travel distance of the vehicle, a time integral over the amount of the longitudinal acceleration of the vehicle, preferably wherein the longitudinal acceleration is weighted with the mass of a train comprising the vehicle. By using several mileage parameters, it can be taken into account and compensated for that the dependence of wear of the wheel on the respective mileage parameter can change under different operating conditions. The mileage parameters are preferred from the time of storing the initial value of the wheel diameter measured in step a). The purpose of using the largest intermediate correction value is to ensure that the true value of the wheel diameter is not greater than the largest intermediate correction value used, so that in the subsequent operation of the vehicle, a speedometer does not indicate a lower driving speed or driving distance than corresponds to reality. Alternatively, the correction value can be calculated as an average of the intermediate correction values.

A variant is also preferred in which a plausibility check is carried out for each reference speed determined in step c) with regard to the initial value of the wheel diameter and the respective value of the rotational speed parameter of the wheel. It is checked whether a (absolute) deviation between the reference speed and a tachometer speed of the vehicle calculated with the initial value of the wheel diameter and the measured value of the rotational speed parameter does not exceed a reference limit value. If the reference limit is exceeded, steps b) and c) are repeated. As a result, measurements of the reference speed, which apparently have large errors, can be rejected.

A variant in which step b) is carried out while the vehicle is in a predefined driving situation is particularly preferred. Typically, step c) is also carried out while the vehicle is in the predefined driving situation. Steps b) and c) are preferably carried out simultaneously. The predefined driving situation can include, for example, in particular in combination with one another: the vehicle is not driven or braked, the roadway runs approximately horizontally (e.g. upward / downward gradient less than 1%), low longitudinal acceleration of the vehicle (e.g. less than 0.2 m / s ² ), Speed in a certain range (e.g. between 30 and 50 km / h) and / or a road condition (e.g. dryness, straightness). This means that there is only a small amount of wheel slip (e.g. less as a 0.5% deviation between a translational longitudinal speed of a center point of the wheel compared to a road surface and a peripheral speed of a point on the rolling circumference of the wheel compared to the axis of rotation of the wheel on the vehicle). The slip can preferably also be measured directly and taken into account in the predefined driving situation. A small slip during the measurement improves the accuracy of the procedure. Alternatively, step b) can be carried out while the slip of the wheel approximately (for example with a maximum of 10% deviation) corresponds to an average slip typically occurring during operation of the vehicle. The average slip is then compensated for when determining a tachometer speed (from the stored value of the wheel diameter and the value of the rotational speed parameter during driving).

A further development of this variant is particularly preferred in which step b) is carried out each time the vehicle is in the predefined driving situation. Many measured values of the rotational speed parameter can then be collected under good measuring conditions. This improves the accuracy of the process.

A further development is also advantageous in which the predefined driving situation is brought about in order to carry out step b). If the predefined driving situation does not occur by itself often enough, it can be brought about in order to be able to record a sufficient number of measured values under good measuring conditions.

A further development is particularly preferred in which the predefined driving situation includes that the vehicle is in a tractionless state. Tractionless means in particular that the vehicle is not driven and is not braked. There is practically no slippage between the wheel and the road. This avoids systematic errors resulting from any slippage when using the method. The wheel diameter can thus be determined particularly precisely.

In an advantageous further development, it is provided that in a travel plan for the vehicle it is predetermined when and / or where the driving situation is brought about. Particularly suitable route sections can be taken into account when drawing up the route plan. This also ensures that the driving situation occurs, so that step b) can be carried out under good conditions.

A variant in which the reference speed is determined independently of location data of the vehicle is particularly preferred. This allows a short individual measurement of the reference speed and the rotational speed parameter to be carried out at the respective measurement time t _i . The measurement conditions then only have to be suitable for a short period of time. In contrast, in a method for determining the reference speed from location data of the vehicle and the elapsed time when driving through an intermediate route, optimal measurement conditions must exist over longer distances and periods. In particular, a measurement duration for determining the reference speed in step c) can be at most 0.5 s, preferably at most 0.3 s. It is also preferred that the vehicle travels at most 50 m, preferably at most 30 m, during the determination of the reference speed in step c). With such short measuring times or measuring distances, too large errors would occur with a location-based determination of the reference speed.

A variant is advantageous which provides that when determining the reference speed in step c), a transit time difference between two measurement signals is taken into account, preferably with the measurement signals being emitted by the vehicle. The determination of the reference speed can, for example, be carried out in a simple manner with a laser system which emits pulsed light signals. Corresponding pulsed sound signals, in particular ultrasound, can also be used.

A variant is particularly preferred which provides that the Doppler effect is used when determining the reference speed in step c). For example, a radar system can be used to determine the reference speed. In particular, the reference speed of a rail vehicle can be measured in a particularly simple and precise manner by means of a radar sensor radiating into a track bed.

A further development of this variant is very particularly preferred, in which it is provided that the reference speed is determined by means of a GPS receiver arranged on the vehicle, and that the GPS receiver provides quality information about the quality of the reference speed. In this way, the reference speed can be determined particularly precisely and with a negligible additional outlay on equipment. A GPS receiver is typically arranged on the vehicle anyway. According to the invention, this is not only used to determine the position, but also the Doppler effect relative to satellites of a GPS system is used to determine the reference speed. The quality information can in particular include: number of satellites at least 12 ° above the horizon, horizontal dilution of precision (HDOP). The quality information can be used to decide whether the previously recorded measured values of the rotational speed parameter and the reference speed should be discarded or taken into account. This improves the reliability and accuracy of the process.

A variant is also advantageous in which it is provided that a control speed is determined for the respective measurement time t _i , preferably the control speed being determined with a distance traveled by the vehicle and the time required for this, and that step d) is only carried out if a deviation, preferably a deviation in terms of amount, of the reference speed from the control speed does not exceed a control limit value. If the control limit value is exceeded, the value of the rotational speed parameter determined in step b) and the reference speed determined in step c) are rejected for this point in time and the method is continued with step b). Errors in the determination of the reference speed can thus be reliably identified and incorrect measurements can be rejected, so that the accuracy and reliability of the method are increased.

A variant is preferred, which is characterized in that a plausibility check is carried out for each estimated value determined in step d) with regard to the initial value of the wheel diameter and / or the estimated values determined at previous measuring times t _i . In particular, each estimated value can be compared with one or more previously determined estimated values. It can also be taken into account here that the wheel diameter becomes smaller and smaller during operation of the vehicle, so that the estimated values also have to become smaller and smaller, at least compared to estimated values that were determined sufficiently far in the past. In the plausibility check, the first mileage parameter can be taken into account, for example by estimating how the current estimated value should differ from an estimated value in the past in view of the difference between the respectively assigned values of the first mileage parameter. As a result, incorrectly determined estimated values can be recognized and rejected, so that they do not have a disadvantageous effect on the quality of the correction value. Erroneous estimates can result in particular from measurement errors in the previous measurements in steps b) and c) or can result from incorrect processing of the measurement results.

A variant is particularly preferred in which it is provided that for each estimated value determined in step d), starting from the initial value of the wheel diameter and the value of the first mileage parameter of the vehicle at the measurement time t _i, an intermediate expected value of the wheel diameter parameter is determined, and that the estimated value is compared with the intermediate expected value of the wheel diameter parameter and the estimated value is rejected if the difference in amount between the estimated value and the intermediate expected value is above an estimated limit value , Findings about the reduction in the wheel diameter with the increase in the first mileage parameter can thus be used to identify incorrectly determined estimated values. These can then be discarded so that they do not adversely affect the quality of the correction value.

Another variant of the method according to the invention provides that an installation value for the wheel diameter is stored and that in the event that the correction value is at least a minimum deviation greater than the initial value and the difference in amount of the correction value and installation value is below an installation limit value, the numerical value of the Output value is replaced by the maximum value or a notification signal is generated. If the expected value of the wheel diameter increases suddenly, which is close to the installation value, it is assumed that it has been forgotten to reset the initial value after installation. According to the variant according to the invention, the initial value is then either automatically set to the installation value or a signal is sent e.g. issued to the driver to initiate a manual reset. The wheel diameter can then be adapted to possibly actually smaller diameters using the method described above.

Further advantages of the invention result from the description and the drawing. Likewise, according to the invention, the features mentioned above and those which have been elaborated further can be used individually or in combination in any combination. The embodiments shown and described are not intended to be a final list to understand, but rather have exemplary character for the description of the invention.

Detailed description of the invention and drawing

Fig. 1a

zeigt ein schematisches Ablaufdiagramm einer ersten Variante eines erfindungsgemäßen Verfahrens zur Ermittlung eines aktuellen Raddurchmessers aus mehreren Messungen eines Drehgeschwindigkeitsparameters eines Rades und einer davon unabhängigen Referenzgeschwindigkeit.

Fig. 1b

zeigt einen Ausschnitt aus einem schematischen Ablaufplan einer ersten Weiterentwicklung der Verfahrensvariante von Fig. 1a mit Berücksichtigung mehrerer, verschiedener Laufleistungsparameter.

Fig. 1c

zeigt einen Ausschnitt aus einem schematischen Ablaufplan einer zweiten Weiterentwicklung der Verfahrensvariante von Fig. 1a mit Berücksichtigung einer Kontrollgeschwindigkeit.

Fig. 1d

zeigt den in Fig. 1a gestrichpunktet dargestellten optionalen Ausschnitt einer speziellen Variante des erfindungsgemäßen Verfahrens, mit dem sprunghafte Anstiege des Raddurchmessers berücksichtigt werden.

Fig. 2a

zeigt ein schematisches Diagramm von gemessenen Werten für einen Drehgeschwindigkeitsparameter aufgetragen über der Zeit der Messung.

Fig. 2b

zeigt ein schematisches Diagramm von zugehörigen Messwerten einer Referenzgeschwindigkeit aufgetragen über der Zeit der Messung.

Fig. 2c

zeigt schematisch die Entwicklung eines ersten Laufleistungsparameters über der Zeit.

Fig. 2d

zeigt ein Diagramm von Schätzwerten für den Raddurchmesser aufgetragen über dem ersten Laufleistungsparameter und eine zugehörige Ausgleichsgerade.

The invention is shown in the drawing.

Fig. 1a

shows a schematic flow diagram of a first variant of a method according to the invention for determining a current wheel diameter from a plurality of measurements of a rotational speed parameter of a wheel and a reference speed which is independent thereof.

Fig. 1b

shows a section of a schematic flow chart of a first further development of the method variant of Fig. 1a taking into account several different mileage parameters.

Fig. 1c

shows a section of a schematic flow chart of a second further development of the method variant of Fig. 1a considering a control speed.

Fig. 1d

shows the in Fig. 1a Optional section, shown in broken lines, of a special variant of the method according to the invention, with which abrupt increases in the wheel diameter are taken into account.

Fig. 2a

shows a schematic diagram of measured values for a rotational speed parameter plotted against the time of the measurement.

Fig. 2b

shows a schematic diagram of associated measured values of a reference speed plotted against the time of the measurement.

Fig. 2c

shows schematically the development of a first mileage parameter over time.

Fig. 2d

shows a diagram of estimated values for the wheel diameter plotted against the first mileage parameter and an associated best-fit line.

The Fig. 3 shows a schematic flow chart of a second variant of a method according to the invention.

The Fig. 1a shows a schematic flow diagram of a first variant of a method according to the invention for determining a current wheel diameter from a plurality of measurements of a rotational speed parameter of a wheel and a reference speed which is independent thereof. First, an output value AW for the wheel diameter of a wheel of a vehicle is stored, for example in an electronic memory element of an on-board computer of the vehicle. A counter Z for measurement sequences is then initialized (set to zero) and then incremented (increased by one). The values of a rotational speed parameter DGP for the wheel and a reference speed VREF that is independent of the rotational speed parameter are then determined in a measurement sequence for a measurement instant t _i . An estimate SW for the wheel diameter is then calculated from the values of the rotational speed parameter DGP and the reference speed VREF. The estimate SW is stored in an estimate store SWS .

Then it is checked whether a predetermined number n of measurement cycles has already been successfully carried out, ie whether n plausible estimated values SW have already been determined. If no, the counter Z for the measurement sequences is increased by one and a new measurement sequence is carried out. If there are n estimated values SW _, a correction value KW for the wheel diameter is determined for an evaluation time t _a . The value of a first mileage parameter 1LLP is also measured for the evaluation time t _a . The first mileage parameter 1LLP can be the distance traveled by the vehicle since the output value AW was determined.

It is then checked whether the correction value KW is plausible. To is based on the measured value of the first mileage parameter 1LLP calculates an expected value EW for the wheel diameter. The expected value EW reflects an experience-based decrease in the wheel diameter compared to the initial value AW with the progression of the first mileage parameter 1LLP. Typically, the expected value EW decreases linearly with the value of the first mileage parameter 1LLP (measured from the time the initial value AW was deposited) from the initial value AW. However, a non-linear dependency can also be applied. This plausibility check checks whether the absolute difference between the correction value KW and the expected value EW is below a plausibility limit PG . That is, it is checked whether the correction value KW is approximately as much smaller than the initial value AW as experience has shown to be the case with the present value of the first mileage parameter.

If the correction value KW is plausible, it is further checked whether the correction value is at least a minimum deviation MA less than the output value AW. If this is not the case, or if the correction value is not plausible, the counter Z is reinitialized and the process sequence described takes place again. If the minimum deviation MA is also observed, the numerical value of the output value AW is replaced by the numerical value of the correction value KW. A new process run can then take place.

The Fig. 1b shows a section of a schematic flow chart of a first further development of the method variant of Fig. 1a with an additional plausibility check based on the first mileage parameter 1LLP. A second mileage parameter 2LLP and a third mileage parameter 3LLP are used in addition to the first mileage parameter 1LLP to calculate intermediate correction values ZKW1 , ZKW2 , ZKW3 .

In addition to the reference speed VREF and the rotational speed parameter DGP, the values of the first mileage parameter 1LLP, the second mileage parameter, are also shown here for each measurement instant t _i 2LLP and the third mileage parameter 3LLP measured. The second mileage parameter 2LLP can be the operating time of the vehicle. The third mileage parameter 3LLP can be the time integral over the longitudinal acceleration of the vehicle weighted with the total mass of a train containing the vehicle.

The value of the first mileage parameter 1LLP is now used to check whether the estimated value SW is plausible compared to the initial value AW, ie whether the estimated value SW is approximately smaller than the initial value AW by an amount determined from the value of the first mileage parameter 1LLP. For this purpose, an intermediate expected value ZEW is determined using the measured value of the first mileage parameter 1LLP and the output value AW. The difference in amount of the estimated value SW and the intermediate expected value ZEW is then compared with an estimated limit value SGW . If the difference in amount is not greater than the estimated limit value SGW, the estimated value SW is considered plausible; otherwise not. Likewise, with the second mileage parameter 2LLP and the third mileage parameter 3LLP, further intermediate expectation values (not shown) can be calculated in a corresponding manner. It can then be required that the estimated value SW is plausible against at least one, at least two or all three intermediate expected values, wherein the estimated limit value SGW or individually different first to third estimated limit values (not shown) can be considered.

If the estimated value SW is not plausible, the rotational speed parameter DGP, the reference speed VREF, the first mileage parameter 1LLP, the second mileage parameter 2LLP and the third mileage parameter 3LLP are measured again. If the estimated value SW is plausible, the estimated value SW in an estimated value memory SWS and the values of the mileage parameters 1LLP, 2LLP, 3LLP each in an associated memory S1L for the first mileage parameter 1LLP, an associated memory S2L for the second mileage parameter 2LLP and an associated memory S3L for the third mileage parameter 3LLP filed. It is understood that all of the memories SWS, S1L, S2L, S3L or some of the memories can be set up on a common data carrier. The memories can also be set up in a common database structure, a common array, a common data matrix or the like.

If the number of stored estimated values SW and the associated values of the mileage parameters 1LLP, 2LLP, 3 LLP is n in each case _, the correction value KW is determined for the evaluation time t _a . The correction value KW is not determined directly here, but rather the respective intermediate correction value ZKW1, ZKW2, ZKW3 is first determined for each mileage parameter 1LLP, 2LLP, 3LLP. For this purpose, a compensation calculation is carried out, which depicts a course of the estimated values SW over the assigned values of the various mileage parameters 1LLP, 2LLP, 3LLP. Typically for each mileage parameter 1LLP, 2LLP, 3LLP a compensation curve, in particular a compensation line, is calculated for the estimated values SW. Each of these compensation curves can then be evaluated for the evaluation time t _{a in} order to obtain the respective intermediate correction values ZKW1, ZKW2 and ZKW3.

The correction value KW is then determined from the intermediate correction values ZKW1, ZKW2 and ZKW3. The largest of the intermediate correction values ZKW1, ZKW2 and ZKW3 can be selected as the correction value KW; KW = max (ZKW1, ZKW2, ZKW3). Alternatively, the correction value KW can be calculated as an average of the intermediate correction values ZKW1, ZKW2, ZKW3, for example KW = (ZKW1 + ZKW2 + ZKW3) / 3 or KW = sqrt [(ZKW1 ^ 2 + ZKW2 ^ 2 + ZKW3 ^ 2) / 3 ]. Then the procedure as for the Fig. 1a described continue.

The Fig. 1c shows a section of a schematic flow chart of a second further development of the method variant of Fig. 1a taking into account a control speed VK . In addition to the reference speed VREF and the rotational speed parameter DGP, the control speed VK is also measured here for each measurement time t _i . Typically, the control speed VK is calculated from the time it takes the vehicle to travel a distance of a known length. In any case, the control speed VK is measured independently of the measurement of the reference speed VREF and the measurement of the rotational speed parameter DGP.

Before an estimated value SW is calculated from the reference speed VREF and the rotational speed parameter DGP, it is checked here whether the reference speed VREF is plausible compared to the control speed VK. For this purpose, the difference in amount of the reference speed VREF and the control speed VK is compared with a control limit value KGW . If the difference in amount is not greater than the control limit value KGW, the reference speed is considered plausible, otherwise not.

If the reference speed VREF is plausible, the estimated value SW is calculated. Otherwise, the measurement of the reference speed VREF of the rotational speed parameter DGP and the control speed VK is repeated. If the estimated value SW has been determined, the method according to the invention can be used as for Fig. 1a described continue. It goes without saying that this plausibility check also applies to the further developed process variant of Fig. 1b can also be used.

In Fig. 1d an additional process section is shown, which is shown in Fig. 1a is shown in broken lines. Here it is checked whether the correction value KW is at least a minimum deviation MA ' greater than the initial value AW, that is to say whether there is a sudden increase in the wheel diameter. In addition, it is checked whether the difference in amount between the correction value KW and an installation value MW (value of the wheel diameter during installation) is below an installation limit value MG . That is, it is checked whether the correction value KW corresponds approximately to the installation value MW. If both are the case, it is assumed that the wheels have been replaced without resetting the initial value. The initial value AW is then replaced by the assembly value MW. The wheel diameter can be adapted as described above.

The FIGS. 2a to 2d illustrate the determination of a correction value KW from measured values for a rotational speed parameter DGP and for a reference speed VREF. In the Fig. 2a measured values of the rotational speed parameter DGP for various measuring times t _i , i = 1 ... n are plotted over time t . The diagram of the Fig. 2b shows schematically the associated values of the reference speed VREF over time t.

The Fig. 2c shows schematically the development of the value of a first mileage parameter 1LLP over time t. In particular, the first running performance parameters 1LLP increases an evaluation time t at _a AWW an evaluation value.

In the Fig. 2d are estimated values SW for the wheel diameter plotted against the first mileage parameter 1LLP. The estimated values SW were each calculated for a measurement instant t _i from the values of the rotational speed parameter DGP and the reference speed VREF. In the Fig. 2d these estimated values SW are plotted over the associated values of the first mileage parameter 1LLP. Furthermore, a best fit line AG is drawn in, which can be determined using the method of least squares. A correction value KW is taken from the compensation line AG, which results from the estimated values SW for the evaluation value AWW of the first mileage parameter 1LLP.

The Fig. 3 shows a schematic flow chart of a second variant of a method according to the invention. The method comprises a measurement sequence MS . In the measurement sequence MS, in particular a reference speed VREF and associated quality information QI , a rotation speed parameter DGP and a first mileage parameter 1LLP are measured. Using the reference speed VREF, the associated quality information QI and information about a traction condition TZ and a road condition FZ is checked whether a predefined Driving situation FS is present. The traction state TZ contains in particular information about whether the wheel is being driven or braked. If the predefined driving situation FS does not exist, a new measuring sequence MS is triggered. If the predefined driving situation FS is present, an estimate SW for the wheel diameter of a wheel of a vehicle is calculated from the reference speed VREF and the rotational speed parameter DGP. This estimated value is checked for plausibility on the basis of the measured value of the first mileage parameter 1LLP and a stored output value AW for the wheel diameter. If the estimated value SW is not plausible, a new measurement sequence MS is triggered. If the estimated value is plausible, it is entered (added) in an estimated value memory SWS.

A correction value KW for the wheel diameter is then calculated on the basis of the estimated values stored in the estimated value memory SWS. Here, the correction value KW is calculated after each new entry of an estimated value SW into the estimated value memory SWS. The number of entries in the estimated value memory SWS can optionally be limited, for example by deleting an old entry when a new estimated value SW is entered, and provided that a predetermined number n of estimated values has already been entered in the estimated value memory SWS (not shown). Alternatively, however, any number of estimated values SW can also be accumulated. The correction value KW is then checked against the initial value AW for plausibility and a sufficient reduction in diameter. If the correction value KW is smaller than the initial value AW by a minimum deviation and has decreased in relation to the initial value AW in accordance with the value of the first mileage parameter 1LLP, the numerical value of the initial value AW is replaced by the numerical value of the corrective value KW. A new measurement sequence MS is then triggered. If the conditions mentioned are not met, a new measurement sequence MS is triggered without updating the numerical value of the output value AW. In addition, the estimated value memory SWS and a possibly existing memory for a first mileage parameter (not shown) can be deleted (emptied).

The stored output value AW and the rotational speed parameter DGP are here further fed to a tachometer T , which calculates a current tachometer speed from their values and updates a distance counter.

In summary, the invention relates to a method for automatically determining a current wheel diameter of a wheel, the diameter of which is constantly decreasing as a result of wear while a vehicle is in operation. An estimated value for the wheel diameter is calculated several times from a rotational speed parameter of the wheel and a reference speed determined independently of it. If the rotational speed parameter DGP is the rotational frequency DF of the wheel, an estimated value SW can be calculated in particular as SW = VREF / (Pi ^∗ DF) from the reference speed VREF. A correction value for the wheel diameter is determined from the large number of estimated values using statistical methods, in particular by means of a compensation calculation. As far as possible, all measured and calculated quantities are subjected to plausibility checks, taking into account empirical values about the wear of the wheel. This prevents an incorrectly determined correction value from being set as the current wheel diameter. The exact features of the claimed method are defined in independent claim 1.

LIST OF REFERENCE NUMBERS

AG

fit line

AW

output value

AWW

evaluation value

DF

rotational frequency

DGP

Rotational speed parameter

EW

expected value

FS

driving situation

FZ

road condition

KGW

control limit

KW

correction value

MA

minimum deviation

MS

measurement sequence

PG

plausibility limit

t _i

Measuring time

t _a

evaluation time

QI

quality information

SGW

estimated limit

SW

estimated value

SWS

Estimate latch

S1L

Memory for the first mileage parameter

S2L

Memory for second mileage parameters

S3L

Third mileage parameter memory

t

time

T

speedometer

TZ

traction state

VK

control speed

VREF

reference speed

Z

counter

ZEW

Between expectation

ZKW1

first intermediate correction value

ZKW2

second intermediate correction value

ZKW3

third intermediate correction value

1LLP

first mileage parameter

2LLP

second mileage parameter

3LLP

third mileage parameter

Claims (16)

1. Method for determining a current wheel diameter of a wheel of a vehicle, in particular of a rail vehicle, comprising the steps of:

   a) storing an initial value (AW) of the wheel diameter,

   b) measuring a rotational speed parameter (DGP) of the wheel for a measuring time (t_i) (i = 1... n),

   c) determining a reference speed (VREF) independent of the rotational speed parameter (DGP) at the measuring time (t_i),

   d) determining an estimated value (SW) of a wheel diameter parameter for the measuring time (t_i) on the basis of the reference speed (VREF) determined in step c) and the value of the rotational speed parameter (DGP) of the wheel measured in step b),

   e) repeating steps b) to d) for different measuring times (t_i),

   f) determining a correction value (KW) of the wheel diameter for an evaluation time (t_a) from the estimated values (SW),

   wherein
   an expected value (EW) of the wheel diameter for the evaluation time (t_a) is determined on the basis of the initial value (AW) of the wheel diameter and a value of a first mileage parameter (1LLP) of the vehicle; and
   the difference in amount between the correction value (KW) and the expected value (EW) is compared with a plausibility limit value (PG), and the correction value (KW) is compared with the initial value (AW) of the wheel diameter; and
   the numerical value of the initial value (AW) is only replaced by the numerical value of the correction value (KW), if the comparison of the difference in amount between the correction value (KW) and the expected value (EW) with the plausibility limit value (PG) shows that the difference in amount between the correction value (KW) and the expected value (EW) is below the plausibility limit value (PG), and if the comparison of the correction value (KW) with the initial value (AW) of the wheel diameter shows that the correction value (KW) is at least a minimum deviation (MA) smaller than the initial value (AW).
2. Method according to claim 1, characterized in that the estimated values (SW) determined in step d) are each assigned a value of the first mileage parameter (1LLP), and
   that, in step f), the correction value (KW) of the wheel diameter is determined by a compensation calculation from the estimated values (SW) and the assigned values of the first mileage parameter (1LLP).
3. Method according to claim 1, characterized in that the estimated values (SW) determined in step d) are each assigned a value of at least two mileage parameters (1LLP, 2LLP, 3LLP),
   that, in step f), for each mileage parameter (1LLP, 2LLP, 3LLP), an intermediate correction value (ZKW1, ZKW2, ZKW3) of the wheel diameter is determined by means of a compensation calculation from the estimated values (SW) and the assigned values of the respective mileage parameter (1LLP, 2LLP, 3LLP), and
   that the correction value (KW) is determined from the intermediate correction values (ZKW1, ZKW2, ZKW3), preferably with the largest intermediate correction value (ZKW1, ZKW2, ZKW3) being used as the correction value (KW).
4. Method according to one of the preceding claims, characterized in that, for each reference speed (VREF) determined in step c), a plausibility check is carried out with regard to the initial value (AW) of the wheel diameter and the respective value of the rotational speed parameter (DGP) of the wheel.
5. Method according to one of the preceding claims, characterized in that step b) is carried out while the vehicle is in a predefined driving situation (FS).
6. Method according to claim 5, characterized in that the predefined driving situation (FS) is brought about in order to carry out step b).
7. Method according to claim 5 or 6, characterized in that the predefined driving situation (FS) comprises that the vehicle is in a tractionless state.
8. Method according to claim 6 or 7, characterized in that it is predetermined in a timetable for the vehicle when and/or where the driving situation (FS) is brought about.
9. Method according to one of the preceding claims, characterized in that the reference speed (VREF) is determined independently of location data of the vehicle.
10. Method according to one of the preceding claims, characterized in that when determining the reference speed (VREF) in step c), a difference in the transit time of two measurement signals is taken into account, preferably with the measurement signals being emitted by the vehicle.
11. Method according to one of the preceding claims, characterized in that the Doppler effect is used in the determination of the reference speed (VREF) in step c).
12. Method according to claim 11, characterized in that the reference speed (VREF) is determined by means of a GPS receiver arranged on the vehicle, and that the GPS receiver provides quality information (QI) about the quality of the reference speed (VREF),
13. Method according to one of the preceding claims, characterized in that a control speed (VK) is determined for the respective measuring time (t_i), preferably wherein the control speed (VK) is determined with a distance traveled by the vehicle and the time required for this, that it is checked whether a deviation, preferably a deviation in amount, of the reference speed (VREF) from the control speed (VK) does not exceed a control limit value (KGW) and that, if the deviation does not exceed the control limit value (KGW) in step d), the estimated value (SW) is calculated from the reference speed (VREF) and the rotational speed parameter (DGP), and, otherwise, the measurement of the reference speed (VREF), the rotational speed parameter (DGP), and the control speed (VK) is repeated.
14. Method according to one of the preceding claims, characterized in that, for each estimated value (SW) determined in step d), a plausibility check is carried out with regard to the initial value (AW) of the wheel diameter and/or the estimated values (SW) determined at previous measuring times (t_i).
15. Method according to one of the preceding claims, characterized in that, for each estimated value (SW) determined in step d) based on the initial value (AW) of the wheel diameter and the value of the first mileage parameter (1LLP) of the vehicle at the measuring time (t_i), an intermediate expected value (ZEW) of the wheel diameter parameter is determined, and
    that the estimated value (SW) is compared with the intermediate expected value (ZEW) of the wheel diameter parameter, and the estimated value (SW) is rejected if the difference in amount between the estimated value (SW) and the intermediate expected value (ZEW) is above an estimated limit value (SGW).
16. Method according to one of the preceding claims, characterized in that an installation value (MW) for the wheel diameter is stored and that, in the event that the correction value (KW) is at least a minimum deviation (MA') greater than the initial value (AW) and the difference in amount of the correction value (KW) and the installation value (MW) is below an installation limit value (MG), the numerical value of the initial value (AW) is replaced by the maximum value (MW), or an information signal is generated.

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